Gear finishing apparatus

ABSTRACT

A gear finishing apparatus having a construction in which a support gear supported by a finishing wheel holding section can support and fix a plurality of finishing wheels in parallel, wherein a finishing wheel holding section makes it possible to move an operating portion for holding and rotating the finishing wheel in a direction parallel to the axis of the finishing wheel and to fix it at predetermined positions within the extent of the movement. If the plurality of finishing wheels are attached to the support gear and the positions thereof are adjusted in advance, a new finishing wheel in an adjusted position can be brought into a processing position by moving and fixing the operating portion of the finishing wheel holding section when one of the attached finishing wheels is worn out, thereby obtaining a rapid and continuous finish processing. Further, if different kinds of finishing wheels are attached in advance, the time required for finishing different kinds of gears to be processed can be reduced.

FIELD OF INDUSTRIAL APPLICATION

The present invention relates to a gear finishing apparatus in which afinishing wheel having internal teeth is rotated so as to finish a gearpiece in mesh with the finishing wheel.

PRIOR ART AND PROBLEMS INVOLVED

When high accuracy in tooth profile is required for a gear, a finishprocessing to modify the gear deformed by a heat-treatment, i.e., aso-called horning is conducted. The finish processing is performed insuch a manner that a finishing wheel meshed with a gear piece (i.e. agear to be processed) at a predetermined crossed axes angle is rotatedso as to modify its tooth profile. The finishing wheel is held in afinishing wheel support gear having a circular form and peripheralexternal teeth for rotation with the finishing wheel. The support gearis rotated by a driving device in mesh with the peripheral externalteeth and is forwarded for cutting into the gear piece. Until thecorrection of the tooth profile is completed, each tooth of thefinishing wheel is repeatedly brought into mesh with a tooth of the gearpiece, generally over a number of times, e.g., 20 to 100 times. Thus,the lifetime of a finishing wheel is generally short.

Conventional gear finishing apparatus have only one finishing wheel foreach one finishing wheel support gear (Japanese Unexamined PatentPublications Nos. 140097/1977 and 365513/1992). Therefore, every timethe finishing wheel has consumed its lifetime, the apparatus must besuspended for replacement with a new finishing wheel. When attaching afinishing wheel, high level accuracy and a careful handling forattachment are required. After the attachment, a dressing treatment isfurther required for correcting positional errors caused by the gapsnecessary for the attachment of the finishing wheel. Therefore,significant time is required for replacing finishing wheels in theprocessing time for finishing a gear, and therefore there has been aneed for time and labor reduction in wheel replacement.

In order to cope with these problems, there has been proposed anapparatus in which an adjustment collar is mounted inside a finishingwheel support gear (Japanese Unexamined Utility Model Publication No.57319/1992). In this apparatus, a finishing wheel of a diameter isreplaced together with a collar having the same diameter so that thereplacement of the finishing wheel can be conducted without detaching agear head. However, this apparatus can not overcome the above problemsoccurring in the mutual replacement of the finishing wheels having thesame diameter. Furthermore, even in replacing a finishing wheel withanother wheel of a different diameter, the apparatus can not eliminatethe necessity of the careful handling for attachment and the dressingtreatment both required for obtaining the above-mentioned high accuracy.

It is an object of the present invention to provide a gear finishingapparatus which can address such demands, perform appropriatereplacement of a gear finishing wheel and reduce the time and laborrequired thereof.

SUMMARY OF THE INVENTION

To fulfill the above object, the present invention provides a gearfinishing apparatus in which a finishing wheel with internal teeth isrotated so as to finish a gear piece in mesh with the finishing wheel,the apparatus comprising:

a base portion;

a work holder which is supported by the machine table and holds the gearpiece;

a sliding section supported on the base portion to move close to andaway from the gear piece on the work holder in a direction substantiallyperpendicular to the axis of the gear; and

a finishing wheel holding section which is supported by the slidingsection and holds the finishing wheel,

the finishing wheel holding section comprising:

a joint portion for holding the finishing wheel at a predeterminedcrossed axes angle relative to the gear piece during processing;

an operating portion movable relative to the joint portion in adirection parallel to the axis of the finishing wheel while holding thefinishing wheel at the crossed axes angle;

a fixing portion for fixing the operating portion to the joint portionat predetermined position within the extent of the movement;

a circular support ring rotating with the finishing wheel which holdsthe finishing wheel inside and is supported by the operating portionrotatablly about the central axis of the support ring; and

a drive portion which is attached to the operating portion and drivesthe support ring to rotate,

wherein the support ring has a sufficient width and an engaging portionso that the plurality of finishing wheels can be arranged thereinadjacent to each other in a direction parallel to the axis of thefinishing wheel and fixed.

The gear finishing apparatus of the present invention has a constructionin which a support ring held by a finishing wheel holding section cansupport and fix a plurality of finishing wheels in parallel inside.Further, a finishing wheel holding section makes it possible to move anoperating portion for holding and rotating the finishing wheel inparallel to the axis of the finishing wheel and to fix it atpredetermined positions within the extent of the movement. Therefore, ifthe plurality of finishing wheels are attached to the support ring andthe positions thereof are adjusted in advance, a new finishing wheelsubjected to positional adjustment can be carried to its processingposition by moving and fixing the operating portion of the holdingsection when one of the finishing gears is worn off, thereby obtaining arapid and continuous finish processing. As set forth, it is possible tobeforehand adjust the positions of the plurality of finishing wheels alltogether, and after starting up processing, it is also possible torapidly shift the worn finishing wheel by moving the operating portion,thereby making appropriate the attachment of finishing wheels and thefinish processing, speeding up the overall operation and simplifying theoperational labor.

The present invention will be more clearly understood from the followingdescription of the embodiments with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation of an embodiment of a gear finishingapparatus according to the present invention;

FIG. 2 is a side elevation of the gear finishing apparatus shown in FIG.1;

FIG. 3 is a plan view of the gear finishing apparatus shown in FIG. 1;

FIG. 4 is a side elevation showing a finishing wheel holding section ofthe gear finishing apparatus shown in FIG. 1;

FIG. 5 is a plan view of the finishing wheel holding section shown inFIG. 4;

FIG. 6 is a front elevation of the finishing wheel holding section shownin FIG. 4;

FIG. 7 is a cross section showing in detail a finishing wheel supportgear of the gear finishing apparatus shown in FIG. 1 and thesurroundings thereof;

FIG. 8 is a longitudinal section showing another example of a finishingwheel fixing ring attached to the finishing wheel support gear; and

FIG. 9 is a plan view of a finishing wheel holding section provided withanother example of a shifter.

EMBODIMENTS

The gear finishing apparatus shown in FIGS. 1 to 3 comprise a baseportion 10 having a table 12 movably provided on a bed 11 and a drivingmotor 13 for moving the table. A work holder 20 is disposed on the table12. The work holder 20 comprises two tail stocks 21 and 22 movable inparallel to the movement of the table and driving cylinders 23 and 24for moving these tail stocks. Behind the table 12 on the bed 11 (rightin FIG. 2) is disposed a sliding section 30 supported so as to move backand forth in the direction substantially perpendicular to the axis ofthe tail stocks. The sliding section 30 comprises a slide body 31 whichmoves along a guide rail 14 on the bed 11, a driving motor 32 fordriving the slide body and a transmission unit 33 for transferring therotation of the output shaft of the driving motor to the reciprocalmotion of the slide body 31. A finishing wheel holder 40 is mounted atthe front end of the slide body 31.

The finishing wheel holding section 40 comprises a joint portion 50connected to the front end of the slide body 31 and an operating portion60 supported by the joint portion. The details of these elements areshown in FIGS. 4 to 6. The joint portion 50 comprises a supporting body51 supported via a bearing 35 to rotate about a supporting shaft 34extending forward from the front end of the slide body 31. At the frontof the slide body 31 is provided a driving motor 52 (FIG. 2), and a rack(not shown) attached to the supporting body 51 meshes with a worm gearattached to the output shaft of the driving motor 52 so that thesupporting body 51 and the supporting shaft 34 are driven to rotateinside the slide body 31. At the area where the front end of the slidebody 31 and the rear end of the supporting body 51 face each other isprovided a fixing portion 53 for stopping the rotation of the supportingbody. The fixing portion 53 comprises: a groove 530 which narrowsoutward and circumferentially extends in the supporting body 51 andopens at the rear face of the supporting body; and a hydraulic cylinderdevice 532 having a cylinder supported by the slide body 31 and aplunger 531 extended toward the supporting body 51 with its headengaging with the groove 530. The fixing portion 53 retracts the plunger531 by hydraulic actuation, to engage with the wall of the groove 530under a high pressure so that the supporting body 51 is fixed not to berotated.

The operating portion 60 comprises: a frame 61 supported by the jointportion 50 to be movable in the axial direction of the finishing wheelas hereinafter described; a finishing wheel support gear 62 for rotationof the finishing wheel which gear is supported by the frame 61 and holdsthe finishing wheel inside; a shifter 63 for moving the frame 61; and afixing portion 66 for fixing the frame 61 at predetermined positionswithin the extent of its movement.

The frame 61 is provided with catches 600 which vertically engage withthe upper and lower edges of the supporting body 51 in such a mannerthat the frame moves along the upper and lower edges of the supportingbody 51. The frame 61 extends forward from the portion connected withthe supporting body 51 to such a large extent as to surround a gearpiece W. At the front portion of the frame 61 is provided an openingportion 610 of a large diameter to which the finishing wheel supportgear 62 is attached. As shown in FIGS. 5 and 7, the support gear 62 isattached so as to be rotatable via a bearing 620 relative to the frame61. The support gear 62 has teeth 621 at its outer periphery. On theupper portion of the frame 61 is mounted a driving portion 64 having amotor. A sprocket wheel 640 is attached to the output shaft of themotor. From the sprocket wheel, a chain 641 extends and meshes with theteeth 621 of the support gear 62.

A hoop ring 65 for holding the finishing wheel is fitted into the insideof the support gear 62. As shown in FIG. 5, the frame 61, the supportgear 62 and the hoop ring 65 are fixedly connected in such a manner thatfixing rings 622 and 623 are screwed to the one side thereof, and fixingring 624, 625 and 626 are screwed to the other side. The hoop ring 65 iscoaxially provided with an engaging projection 650 at the center of theinner surface, and the diameters of the portion adjacent to both sidesof the projection correspond to the outer diameters of finishing wheelsto be held. Around finishing wheels A₁ and A₂ fitted into both sides ofthe engaging projection 650 are attached fixing rings 651 and 652 whichare then screwed to the hoop ring 65 for fixing the finishing wheels A₁and A₂.

A piston 630 of the sliding section 63 is mounted at the rear of theframe 61 as shown in FIGS. 4 and 5. The piston is secured to the frame61 at its one end 631, and the other end fits movably into a cylinderbore 510 formed in the supporting body 51 of the joint portion 50 toform a piston head 632. Into the cylinder bore 510 extends oil passages511 and 512 in communication with a hydraulic apparatus not shown in thedrawing. Therefore, hydraulic oil is compressedly sent through the oilpassages 511 and 512 so that the piston 630 can be moved to shift theframe 61 relative to the joint portion 50. It is also possible toarrange the sliding section 63 in such a converse manner that the piston630 is connected to the supporting body 51, and the cylinder bore 510 isformed in the frame 61.

A fixing device 66 is provided at the area where the supporting body 53of the joint portion and the frame 61 face each other. As shown in FIG.4, the supporting portion 53 is provided with a groove 513 which narrowsoutward and extends to the direction of the movement of the frame 61. Atthe rear end of the frame 61 is provided with a plunger 660 the endportion of which engages with the groove and a hydraulic cylinder 661for advancing and retracting the plunger. By actuating the hydrauliccylinder 661, the plunger 660 is retracted so as to engage with thegroove 513 under a high pressure, thereby fixing the frame 61 to theslide body 51. The fixing devices 66 are provided at four locations inthe frame 61 as shown in FIG. 6.

The present gear finishing apparatus works as follows. Firstly, twofinishing wheels A₁ and A₂ are attached to the hoop ring 65 beforestarting a finish processing. During attaching the wheels, an accuratepositional adjustment and a dressing treatment for correcting attachmenterrors are conducted for both of the wheels. An arbor is attached to agear piece in such a manner that it projects from each side of the gear.The ends of the arbor is pinched between the tail stocks 21 and 22 forfixing the gear piece on the table. At this time, the slide body 31 isin a retracted position as shown in FIG. 2. The slide body 30 isadvanced from this position by the driving motor 32 so that thefinishing wheels A₁ or A₂ is brought into mesh with the gear piece.Next, the driving portion 64 is actuated so as to rotate the supportgear together with the finishing wheels, and then the slide body 31 isadvanced to a predetermined depth of cut. When the finish processing ofthe gear piece is completed by the rotation of the finishing wheels andthe appropriate repetition of the reciprocal motion of the table 12, thedriving portion 64 is stopped, then the slide body 31 is retracted, andthe clamping of the tail stocks 21 and 22 are released so as to take outthe gear piece.

When one of the finishing wheels (for example, A₁) is worn off by therepetition of finish processings, the sliding section 63 is actuated toshift the frame 61 so that the other finishing wheel (for example, A₂)comes into a processing position. Therefore, it is not necessary todetach the finishing wheel for replacement so that a finish processingcan be continued with another new wheel.

Instead of the above-mentioned hydraulic cylinder, a sliding section 63'may be provided with a ball screw 634 (feed screw) in the supportingbody 51 of the joint portion 50, a servo motor 635 for driving the ballscrew and a coupling 636 between them, wherein a female screw 637 tomesh with the ball screw is fixed to the frame 61 as shown in FIG. 9.Further, these elements may be connected in such a converse manner thatthe frame 61 is provided with the ball screw (feed screw), the drivingmotor and the coupling, and that the supporting body 51 is provided withthe female screw 637.

With reference to the above embodiments, the apparatus of the typehaving two finishing wheels have been described. It is also possible toattach three or more finishing wheels by appropriately changing thedesign of the hoop ring etc. FIG. 8 shows one example of such a hoopring. This hoop ring 65' comprises an engaging projection 653 locatedabout one third width away from one edge of the hoop ring. An engagingring 655 is fitted at a distance of about one third width away from theother edge. For attachment of the wheels, the wheels A₁ and A₂ arefitted in both sides of the engaging projection 653 after detaching theengaging ring 655, and thereafter the engaging ring 655 is fittedthereinto. Furthermore, the wheel A₃ is fitted so far as to contact theengaging ring 655. Then, fixing rings 657 and 658 are screwed to strideacross the ends of the hoop ring 65' and the peripheries of the wheelsA₁ and A₃ are screwed, whereby three finishing wheels can be fastened.More finishing wheels can be attached when using a wider hoop ring andthe required numbers of engaging rings 655 spaced apart from each otherby the width of a finishing wheel to be attached.

Further, when attaching a plurality of different kinds of finishingwheels to the present finishing apparatus, it is possible to rapidlyconduct necessary processings on different kinds of gears to beprocessed without detaching the finishing wheels for replacement. Inthis case, by providing a discriminator for discriminating differentkinds of gears to be processed and a controller for controlling theposition of the sliding section in accordance with the discriminationresult, it is possible to automatically finish different kinds of gears.

While having described the embodiments of the present invention, thepresent invention is not limited to these embodiments, and variouschanges may be made without departing from the scope of the presentinvention.

We claim:
 1. A gear finishing apparatus in which a finishing wheel withinternal teeth is rotated so as to finish a gear piece in mesh with thefinishing wheel, the apparatus comprising:a base portion; a work holdersupported by a machine table and for holding the gear piece; a slidingsection supported on the base portion and movable close to and away fromthe gear piece on the work holder in a direction substantiallyperpendicular to the axis of the gear; and a finishing wheel holdingsection supported by the sliding section and for holding the finishingwheel, the sliding section having a supporting shaft extending from thesliding section toward the gear piece along the sliding direction of thesliding section. the finishing wheel holding section comprising:a jointportion supported by the supporting shaft and holding the finishingwheel at a selected crossed axes angle relative to the gear piece duringprocessing; an operating portion movable relative to the joint portionin a direction parallel to the axis of the finishing wheel while holdingthe finishing wheel at the crossed axes angle; a fixing portion forfixing the operation portion to the joint portion at predeterminedpositions within the extent of the movement; a circular support ringrotating with the finishing wheel and holding the finishing wheeltherein, said circular support ring being supported rotatably about acentral axis thereof by the operating portion; and a drive portionattached to the operating portion and for driving the support ring torotate, wherein the support ring has a sufficient width and an engagingportion so that a plurality of individual finishing wheels can bearranged and fixed therein adjacent to each other in a directionparallel to the axis of the finishing wheel.
 2. A gear finishingapparatus according to claim 1, wherein the work holder comprises a tailstock movable on the machine table, and wherein the sliding section ismovable perpendicularly to the movement of the tail stock.
 3. A gearfinishing apparatus according to claim 1, wherein the operating portioncomprises a frame for receiving the support ring inside of an openingand for holding the support ring rotatably about its axis and fixedly ina direction along its axis.
 4. A gear finishing apparatus according toclaim 3, wherein the operating portion comprises a shifter consisting ofa hydraulic cylinder and a piston connected to the one and the other ofthe joint portion and the frame in order to move the finishing wheel inparallel to its axis relative to the joint portion.
 5. A gear finishingapparatus according to claim 3, wherein the operating portion comprisesa feed screw and a driving device thereof connected to the one and theother of the joint portion and the frame; and a female screw portion inmesh with the feed screw in order to move the finishing wheel inparallel to its axis relative to the joint portion.
 6. A gear finishingapparatus according to claim 1, wherein the support ring comprises agear having external teeth, and wherein the rotational drive portionmeshes with the external teeth of the support ring so as to drive it. 7.A gear finishing apparatus according to claim 1, wherein the engagingportion of the support ring comprises a convex portion extendingconcentrically along the center of the inner surface of the wheel, andwherein the finishing wheels accommodated in both sides of the convexportion are fixed by fixing rings attached to both sides of the supportring.
 8. A gear finishing apparatus according to claim 1, wherein theengaging portion of the support ring comprises at least one engagingring having such an outer diameter as to be closely fitted into thesupport ring, and wherein the plurality of finishing wheels areaccommodated in the support ring with the engaging rings interposedtherebetween and are fixed by the fixing rings attached to both sides ofthe support ring.
 9. A gear finishing apparatus according to, claim 1,wherein the engaging portion of the support ring comprises a convexportion extending concentrically along the inner surface and at leastone engaging ring having such an outer diameter as to be closely fittedinto the support ring, and wherein the plurality of finishing wheels areaccommodated in the support ring with the engaging rings interposedtherebetween and are fixed by the fixing rings attached to both sides ofthe support ring.